Clearing the Air
By Mark S. Nemeth  #45776

This article originally ran in the March/April 2001 issue of
Escapees magazine
Reprinted by permission

Dottie's article in the Nov/Dec issue of the Escapees magazine about John and Martha and their deadly encounter with Carbon Monoxide (CO) has stirred up a bit of controversy among the membership. Technical issues aside, the story was one that desperately needed to be told. It was terribly foolhardy to place a portable generator in an essentially unvented compartment and not provide for a proper exhaust system to remove deadly combustion byproducts. It is even worse to have lives lost when a small amount of prevention would have saved the day. That small prevention that I'm referring to is a functional Carbon Monoxide (CO) Detector installed inside your RV. Such a device would most likely have saved John and Marsha's lives. Do you have one yet? If not, then what are you waiting for? If you are not convinced that CO poses a very real threat to your health and indeed your very life, then read on!

CO is a highly toxic gas that can kill at small concentrations of 300 parts per million (ppm) or less. Carbon monoxide gas is produced when fossil fuel burns incompletely because of insufficient oxygen. In properly installed and maintained appliances gas burns clean and produces only small amounts of carbon monoxide. Anything that disrupts the burning process or results in a shortage of oxygen can increase carbon monoxide production. Wood, coal, and charcoal fires always produce carbon monoxide, as do gasoline engines. Potential sources of CO can include a malfunctioning propane furnace or ventless heater, exhaust from a generator or gasoline engine or a wood or charcoal fired BBQ or stove. The fact that CO is a colorless, odorless, tasteless, and non-irritating poison compounds the problem. When exposed to high concentrations, persons become dizzy, are unable to stand or move out of the space, and often collapse. The brain does not receive sufficient oxygen during a CO exposure resulting in confusion. Because it takes several hours for the body to remove carbon monoxide, CO is a cumulative poison. The amount of CO in the body continues to increase while breathing CO in the air. OSHA places the maximum allowable concentration for continuous exposure for healthy adults in any 8-hour period at only 50 ppm!

Smaller living spaces increase the concentration of carbon monoxide. For instance, operation of a defective unvented gas heater in a 1680 square foot home might raise CO levels to 30 ppm. In a 200 square foot RV, the same heater could quickly raise the CO concentrations to a dangerous 200 ppm or more. The problem is further compounded by failing to provide adequate ventilation to supply oxygen for combustion and to carry away combustion products.

Well, consider this: Gas kitchen ranges release unvented combustion products into the interior of your RV. The amount of CO in combustion products varies widely, from a few ppm from a properly operating gas burner to 20,000-30,000 ppm from an improperly operating gas burner. Contrary to popular belief, carbon monoxide can, and often is, produced from a blue burning flame. Carbon monoxide concentrations in the kitchen are elevated when the stove is used without using the range hood.

How important is the use of an exhaust hood vented to the outdoors? Very. Even when the kitchen range is operating properly, there will be some carbon monoxide produced along with carbon dioxide, nitrogen dioxide, and water vapor. Kitchen range manufacturers recommend use of a range hood to exhaust the combustion products along with cooking odors, grease and moisture produced during cooking.

  • Still not convinced that you need a detector?
  • If you have a generator installed in your rig, or use a portable unit, you need a detector even more!

    The National Institute for Occupational Safety and Health (NIOSH) ran a 5.5 horsepower gasoline-powered pressure washer in a double garage with both doors open, the window open, and a vent open. In only 12 minutes CO concentrations in the garage rose to 658 ppm. The rate of emission from a typical gasoline engine is so large (30,000 to 100,000 ppm) that it is very difficult to provide sufficient ventilation. NIOSH warns, "Do not use equipment and tools powered by gasoline engines inside buildings..."

    Even with a properly installed exhaust system, CO from your (or even your neighbor's) running generator can still enter your rig through small cracks or even waft into your rig through an open window. As the above NIOSH test proves, just because the windows in your rig are open doesn't necessarily protect you from potentially dangerous concentrations of CO.

    If not, then consider this:

    Many Rvers who like to dry camp have installed unvented propane space heaters. These units are great for saving propane and battery power, but can be a source of indoor air pollution and that includes CO! When properly maintained and adjusted, gas heaters produce low amounts of carbon monoxide. One cause of carbon monoxide poisoning from unvented heaters-- incomplete combustion caused by lack of air--has been virtually eliminated in newer heaters by use of Oxygen Depletion Sensors (ODS). Unfortunately, the ODS does not respond to incomplete combustion caused by improper gas pressure, dust, dirt, or rust on the burner or disruption of the burner by air currents. Even a properly maintained and adjusted vent free heater can cause dangerous levels of CO inside an RV if adequate ventilation is not provided….

    Standard RV forced air furnaces are very safe, as all combustion gasses are vented outside the rig by a forced air blower system. However, as these units age, the furnace combustion chamber can corrode or split causing combustion byproducts to enter the RV and build up. In the case of such a malfunction, without a functional CO detector installed in your rig, your only early warning signal will be the onset of flue like symptoms, nausea or dizziness as the levels of CO rise. You may fail to recognize these symptoms as warnings of CO poisoning until it is too late.

    I hope all the above has convinced you to protect yourself by installing a CO detector! What possible reason can you come up with that would justify NOT having one in your rig? They aren't terribly expensive: even the best ones will set you back less than a tank of gas or diesel. They are easy to operate, easy to install and will give you peace of mind along with serious protection. CO kills more people every year than all other forms of poisoning combined. Each year over 3,800 people die, and more than 10,000 individuals seek medical attention or miss work. Up to 40% of the survivors of acute CO poisoning develop memory impairment and other serious, permanent health problems.

    I believe that the best detector to purchase is one with a digital display. That lets you monitor even lower levels of CO that may be too low to cause an alarm, but high enough to be dangerous with long term exposure. Most detectors with digital readouts also capture and hold the peak CO reading since the last reset. This is worth keeping an eye on too. Cheaper units that are alarm only will still provide protection and be way better than nothing at all. Walmart carries CO detectors, as do most building supply, hardware and department stores. All you have to do now is go get one. Do it now! …. I'll wait…..

     Great! Let's install it. Read the manual and install the batteries. Pick a location on the wall that is approximately midway between the floor and ceiling. Since CO is not significantly lighter or heavier than air, it tends to disperse evenly. Make sure the detector is not behind curtains or furnishings. CO must be able to reach the detector for the unit to work. It's best to avoid installing the detector real close to the kitchen stove or propane heater and keep it out of the moist bathroom areas. A single detector, placed centrally in your rig, will provide adequate protection. Follow the instructions in the user manual that came with your unit. Test it regularly and keep it free of dust and dirt and it will continue to provide you with peace of mind for years to come! Highly recommended is the Iowa State University Extension site for Carbon Monoxide Information.

    Be sure to click on the link to 'Carbon monoxide information from ISU Agricultural and Biosystems Engineering' Here, you will learn many facts about CO and it's dangers and properties. The following link is a shortcut to this informative page:

    For more information, you might want to check these agencies out:



    Here are some links to Carbon Monoxide Detector Sources and Manufacturers online:



    Senco Sensors

    This page last updated on 09/09/12